package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 * <p>LUA是保证redis中的线程安全问题，直接把前四步放lua中，相当于加了同步锁。但你开启新的线程去是兜底的方式去使用乐观锁解决超卖，分布式redis解决一人一单分布式的线程问题。<</p>
 *
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    //创建阻塞队列
    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024*1024);
    //异步处理线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    //类初始化后执行
    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    //用于线程池处理的任务
    private class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            while(true){
                try {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucher(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常",e);
                }
            }
        }
    }

    private void handleVoucher(VoucherOrder voucherOrder) {
        //1.获取用户
        Long userid = voucherOrder.getUserId();
        //2.创建锁对象
        RLock lock = redissonClient.getLock("lock:order" + userid);
        //3.获取锁对象
        boolean isLock = lock.tryLock();
        //4.上锁失败，说明单个用户在并发下单
        if (!isLock) {
            log.error("不允许重复判断");
            return ;
        }
        try {
            //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            //释放锁
            lock.unlock();
        }
    }

    private IVoucherOrderService proxy;
    @Override
    public Result seckillVoucher(Long voucherId) {
       //获取用户
        Long userId = UserHolder.getUser().getId();

        long orderId = redisIdWorker.nextId("order");
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),userId.toString(),String.valueOf(orderId));

        int r = result.intValue();
        //2.判断结果是否为0
        if(r!=0){
            return Result.fail(r==1?"库存不足":"不能重复下单");
        }

        //为0，有资格，把下单信息保存到阻塞队列中
        //2.0创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        //2.1订单id
        voucherOrder.setId(orderId);
        voucherOrder.setUserId(userId);
        //2.3代金券id
        voucherOrder.setVoucherId(voucherId);
        //2.4放入阻塞队列
        orderTasks.add(voucherOrder);

        //3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        //3=4.返回订单id
        return Result.ok(orderId);

    }

/*    @Override
    public Result seckillVoucher(Long voucherId) {
        //1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        //2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            return Result.fail("秒杀尚未开始！");
        }
        //3.判断秒杀是否结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            return Result.fail("秒杀已经结束！");
        }
        //4.判断是否库存充足
        if (voucher.getStock()<1) {
            return Result.fail("库存不足");
        }
        Long userid = UserHolder.getUser().getId();
        //创建锁对象
//        SimpleRedisLock lock = new SimpleRedisLock("order" + userid, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order" + userid);
        //获取锁对象
        boolean isLock = lock.tryLock();
        //上锁失败，说明单个用户在并发下单
        if (!isLock) {
            return Result.fail("不允许重复下单");
        }
        try {
            //获取代理对象
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } finally {
            //释放锁
            lock.unlock();
        }

    }*/

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {

        Long userid = voucherOrder.getUserId();
        //5.一人一单逻辑
        //5.1用户id
        int count = query().eq("user_id", userid).eq("voucher_id", voucherOrder.getVoucherId()).count();
        //5.2判断是否存在
        if(count>0){
            //用户已经购买过了
            log.error("用户已经购买过一次");
            return;
        }
        //6.扣减库存|第一个update获取更新器对象
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock -1")//set
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock",0)//where stock >0
                .update();

        if(!success){
            log.error("库存不足");
            return;
        }
        //创建订单
        save(voucherOrder);
    }
}
